The inventive concept relates to an apparatus for generating a random number, and more particularly, to an apparatus for generating a random number by generating a metastable state signal using logic gates.
Metastability is widely used in a true random number generator (TRNG) since it is known to have good stochastic properties. A TRNG, for example, can take the form of a module added to a computer for the purpose of generating true (or truly) random numbers. Conventionally, to use metastability, a latch or a flip-flop has been mainly used. However, due to various factors, such as mismatches between transistors, temperature imbalance inside a chip, ionizing radiation, or parasitic fluctuation of output voltages, the probability that a physical flip-flop circuit will stay in a metastable region is very low. Natural metastability rarely occurs and, thus, it is inefficient to use the metastable phenomenon of the flip-flop circuit as a basis for a reliable TRNG. That is, the natural occurrence of metastability is very rare, thus causing a reduction in the value of either accumulated entropy or TRNG throughput.